The present study investigated the aptness of assessing the levels of progastrin‑releasing peptide (Pro‑GRP) in addition to the T lymphocyte subpopulation in lung cancer patients prior to and after therapy for determining immune function. A total of 45 patients with lung cancer were recruited and stratified in to a non‑small cell lung cancer (NSCLC) and an SCLC group. Prior to and after treatment by combined biological therapy comprising chemotherapy or chemoradiotherapy followed by three cycles of retransformation of autologous dendritic cells‑cytokine‑induced killer cells (DC‑CIK), the peripheral blood was assessed for populations of CD3+, CD4+, CD8+ and regulatory T cells (Treg) by flow cytometry, and for the levels of pro‑GRP, carcinoembryonic antigen, neuron‑specific enolase and Cyfra 21‑1. The results revealed that in NSCLC patients, CD8+ T lymphocytes and Treg populations were decreased, and that CD3+ and CD4+ T lymphocytes as well as the CD4+/CD8+ ratio were increased after therapy; in SCLC patients, CD3+, CD4+ and CD8+ T lymphocytes were increased, while Treg cells were decreased after treatment compared with those at baseline. In each group, Pro‑GRP was decreased compared with that prior to treatment, and in the SCLC group only, an obvious negative correlation was identified between Pro‑GRP and the T lymphocyte subpopulation. Furthermore, a significant correlation between Pro‑GRP and Tregs was identified in each group. In conclusion, the present study revealed that the immune function of the patients was improved after biological therapy. The results suggested a significant correlation between Pro‑GRP and the T lymphocyte subpopulation in SCLC patients. Detection of Pro‑GRP may assist the early clinical diagnosis of SCLC and may also be used to assess the immune regulatory function of patients along with the T lymphocyte subpopulation. Biological therapy with retransformed autologous DC‑CIK was indicated to enhance the specific elimination of tumor cells and improve the immune surveillance function in cancer patients, and also restrained the immune evasion of the tumor, leading to decreased Pro‑GRP levels.

Related Articles